Means for mounting debarking tools on an annular debarking rotor



United States Patent inventors Karl-Erik A. Jonsson Gavle, Sweden;

August Matlik, Gavle, Sweden Appl. No. 703,387 Filed Feb. 6, I968 Patented Aug. ll, 1970 Assignee Brundell Och .Ionsson AB, Gavle, Sweden 2 Corp. of Sweden Priority Feb. 17, 1967 Sweden 2,229/67 MEANS FOR MOUNTING DEBARKING TOOLS ON AN ANNULAR DEBARKING ROTOR 2 Claims, 2 Drawing Figs.

US. Cl 144/208, 92/3l Int. Cl B27l 1/00, FOlb 3/00 [50] Field of Search l44/208-5, 208-4, 208; 92/3 I 9 H6] [56] References Cited UNITED STATES PATENTS 2,688,95l 9/l 954 Sears 92/3 I X 3, l 96,9 1 2 7/l 965 Brundell et al 144/208-1 3,357,182 12/1965 Jacoby 92/31 Primary Examiner- Gil Weidenfeld Attorney-Bauer and Goodman ABSTRACT: An improved log debarking machine having an annular debarking rotor and at least one deharking tool mounted on said rotor. The improvement comprises mounting said rotor on a rotatable shaft which is a piston provided with a helical thread which coacts with a corresponding thread on the inside ofa cylinder surrounding the piston. One end ofthe piston is acted upon by a resilient force striving to screw the piston in such direction that the tool is rotated onto the axis of the rotor while moving simultaneously axially oppositely to .the intended direction ofinfeed ofa log.

PRESSURE ACCUMULATOR Patehted Aug. 11, 1910 3,523,564

P SURE ACCU ULATOR INV E NTDRS KQId-ER'IK kdonsson Au usu mu i K MEANS FOR MOUNTING DEBARKING TOOLS ON AN ANNULAR DEBARKING ROTOR BACKGROUND OF THE INVENTION The invention relates to means for mounting a debarking tool on an annular debarking rotor. In the known way, such means comprise a rotatable shaft carried by the rotor in parallel to the axis of the rotor and actuated by a resilient torsional force in such direction that the tool'is caused to engage the surface of a log passing through the rotor. Generally, a plurality of tools are mounted in spaced relationship on the rotor.

When a log is fed axially towards the rotating rotor and its fore end hits the lateral edges of the tools, said edges engage the log so that the tools are rotated automatically by a screw action, and the debarking edges at the end of the tools come to rest on the cylindrical surface of the log. This self-opening" action is facilitated, if said lateral edges of the tools are sharp.

SUMMARY OF THE INVENTION The invention is particularly valuable in connection with such a self-opening action but it may also be designed to achieve other advantages, as will be apparent hereinafter. According to the invention, thetool carrying shaft comprises a piston provided with at least one helical thread arranged to coact with a corresponding thread on the inside of a cylinder surrounding the piston. Further, one end of the piston is acted upon by a resilient force striving to screw the piston in such direction that the tool is rotated inwardly to the axis of the rotor while moving simultaneously axially oppositely to the intended direction of infeed of a log. Of course, such coacting threads must have a pitch which permits the piston to be screwed when influenced by a reasonable axial force. During its opening'movement a tool mounted in this way will thus be moved in the direction of infeed against the action of a resilient force which considerably reduces the strain to which the tool and the rotor are subjected by the impact of the log end. Another advantageous effect in this connection is that the advancement of the log is not temporarily stopped but the log can move forward at practically unchanged speed.

Preferably the resilient force acting upon the piston is obtained'from a pressure accumulator which transfers a resilient pressure to a quantity of oil filling a cylinder room at the inner end of the piston. Devices of this kind have been shown in FIGURES 3 and 3a of the US. patent No. 3, 196, 912, for instance. A certain advantage of this embodiment is that the bearing surfaces of the rotatable parts will be effectively lubricated by the pressurized oil. Of course, the piston may be provided with common screw thread, in which case the cylinder is threaded as a nut, but in a preferred embodiment both members contain thread grooves together accommodating balls as in a screw ball bearing known per se. In this way, the rotation of the tool is considerably facilitated.

BRIEF DESCRIPTION OF THE DRAWING 'The invention will be described in more detail with reference to the accompanying drawing, in which:

FIGURE 1 shows diagrammatically a debarking seen from the infeed end, while FIGURE 2 shows an axial section of an embodiment of the mounting means according to the invention.

- DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The annular rotor 4 in FIG. 1 is journalled in a surrounding stator 3. At its inlet end the rotor 4 carries three blade-shaped debarking tools 5 evenly spaced around the circumference. The tools 5 are pivotable in a plane perpendicular to the axis of the rotor, and their debarking edges are parallel to the axis of the rotor. In the initial position shown, the tools are directed almost radially inwards so that the debarking edges 6 are located at a slight distance only from each other. The rotor shown in FIG. I is adapted to be rotated in anti-clockwise direction and the tools 5 must thus be mounted to pivot anticlockwise against the action of resilient forces so that they can climb onto a log advanced axially towards the rotor. To facilitate the climbing or self-opening action,.it is customary that the tools have lateral edges 7 projecting a little axially to engage the end surface of the log.

According to the invention (FIG. 2), each tool 5 is mounted in a holder 8 secured to the outer end of a piston 10 which protrudes from a cylinder 9. The cylinder is composed of a cylindrical member 11, an annular end cap 12 surrounding the piston 10 and a rear end cap 14 connected to a conduit 15 for supply of pressure fluid. A lip seal ring I3 surrounds the piston 10 in the cap 12. Within the cylinder 11 the piston has a portion 16 with a somewhat larger diameter though smaller than the inner diameter of the surrounding cylinder wall so that an annular space 17 is formed. The rear end of the piston has a widened head 18 which is movable with clearance in a chamber 19 defined by the rear end cap 14. In its foremost limit position the head 18 rests against an annular shoulder 20 provided in the cylinder 11.

The central portion 16 of the piston is formed with a thread groove 21 semicircular in cross section, and a corresponding thread groove facing the groove 21 is formed in the inner surface of the cylinder 11. A number of balls 23 engaging both grooves 21,22 are kept spaced around the circumference by means of a ball holding sleeve 24 inserted in the annular space 17 and provided with a hole for each ball.

When pressure fluid, preferably oil, is supplied through the conduit 15, the piston 10 is rotated into its omit position shown in FIG. 2, where the head 18 rests against the shoulder 20. The cylinder 9 is secured in the rotor 4 in such a way that said limit position of the piston 10 corresponds to the initial tool position shown in FIG. I. As appears from FIG. 2, the thread grooves 21,22 are cut in such direction that the tool 5 is moved anti-clockwise when the piston 10 is screwed backwards from its foremost position. When the tool is subjected to the pressure of a log fed axially towards the rotor, it is thus moved backwards simultaneously with its movement in opening direction. Of course, the force acting upon the piston must be resilient and, as mentioned, this can be achieved by various means. In practice, the thread pitch should probably be slightly greater than shown in FIG. 2, and the threads may, for instance, form an angle of 45 to the axis of the piston.

As mentioned above, also an effective lubrication of the rotatable members is obtained, because the oil penetrates as far as to the lip seal 13 inserted in the fore end cap 12. Another effect, not mentioned previously, is that during the latter part of its movement towards the shoulder 20 the end head 18 of the piston gives a desirable damping of the piston stroke, because oil is squeezed from the space 17 into the chamber 19. Such a damping eliminates an otherwise occurring impact when the tool slides off the surface of a log and thus is rapidly rotated clockwise into its initial position shown in FIG. 1.

It should be noted that the thread pitch must of course be reversed, if the rotor shown in FIG. I is to rotate clockwise instead. A different embodiment is also required, if the tools are instead mounted at the outlet end of the rotor, in which case they are moved away from the rotor by a log advanced, but basically the function remains the same. Further, it is obvious that the piston 10 may be provided with two or more parallel threads cooperating with corresponding threads in the wall of the cylinder 9.

We claim:

1. In a log debarking machine having an annular debarking rotor through which logs are to be moved axially, said rotor containing at least one leg debarking tool extending radially inwardly, the improvement being means for mounting said debarking tool, said means comprising;

a cylinder carried by the rotor with its axisparallel to the axis of the rotor, said cylinder having a piston movably positioned therein and protruding from one end thereof;

tion of said rotor; and

means to limit the rotation of said piston when the free end of said debarking tool has reached an inner predetermined position in the radial direction;

whereby when said debarking tool is hit by the advancing end of a log to be debarked said tool is caused to rotate and move radially outwardly from its said predetermined position and is simultaneously caused to move a small distance axially in the feed direction of said log thereby reducing the effect of the impact. 2. Means as claimed in Claim 1, characterized in that the piston and the cylinder are provided with thread grooves facing each other and connected by balls.

tended direction of rotation of said rotor when said piston moves axially in the feed direction of a log being debarked;

means acting axially on said piston to cause it to rotate in the direction opposite to the intended direction of rota- 

